1. Field of the Invention
The present invention generally relates to a metal trench de-noise structure. In particular, the present invention is directed to a deep metal trench de-noise structure, to avoid sensitive signal region interfering with coupling noise in the substrate.
2. Description of the Prior Art
Generally speaking, as shown in FIG. 11, semiconductor elements are usually various semiconductor elements 40 disposed on the element region 41 of the substrate 10. Optionally, the element region 41 may include various electronic elements. For example, various adjacent element regions 41 include electronic elements generating different types of signals. For instance, various adjacent element regions 41 may be a digital circuit element region 42, a radio frequency (RF) circuit element region 43, or an analog circuit element region 44. Because element regions 40 of different functions generate different types of signals, these signals may couple one another by means of the substrate, to be the noise of other signals.
Generally speaking, element regions 40 of different functions tolerate noise differently. For example, a digital circuit element region 42 generates digital signals. On one hand, the quality of a digital signal is indifferent to a considerable amount of noise which the digital signal itself carries. On the other hand, either a pure digital signal itself or its associated noise is likely to become the noise of other kinds of more sensitive signal types. In other words, the digital signal itself is indifferent to noise, but it could be the source of noise to other types of signals which are more sensitive to noise.
As far as the analogue circuit element region 44 or the RF circuit element region 43 is concerned, they are less tolerant to noise than a digital circuit element region 42, in particular different RF circuit element regions 43 may also interfere with one another. For example, it is possible that different RF circuit element regions 43 of the same frequency may even interfere with one another when they are too close to each other. Or, when different RF circuit element regions 43 of high/low frequencies RF type regions 43 are too close to each other, mutual interference between different type regions thus happens. Different analog circuit element regions 44 may interfere with one another, too. Considering the increasing element density on chips and different element regions are getting closer and closer to each other, they intensify the interference of noise. Therefore, a new way is still needed to minimize the noise as much as possible or to even eliminate the noise or the interference among different element regions through the substrate. Preferably, the solution is also compatible with the current semiconductor manufacturing process.